1. Field of the Invention
This invention relates to a flat panel display device, and more particularly to a method of driving a plasma display panel(PDP) that is capable of improving the brightness of the PDP and an apparatus thereof.
2. Description of the Prior Art
Nowadays, there have been actively developed flat panel display devices such as a liquid crystal display(LCD), a field emission display(FED), a plasma display panel (PDP) and so on. In the flat panel display devices, the PDP has advantages in that its manufacturing is easy due to its simple structure and that it has a high brightness and a high luminous efficiency compared with other flat panel display devices. Also, the PDP provides the improved memory ability and a wide light view angle of more than 160xc2x0 C. Furthermore, the PDP device has an advantage in that it can implement a large-scale screen of more than 40 inches. Such a PDP is classified into a direct current(DC) system and an alternating current(AC) system. As shown in FIG. 1, the PDP of conventional AC system includes a lower glass substrate 10 mounted with address electrodes 12 and an upper glass substrate 20 mounted with a sustaining electrode pair 22. On the lower glass substrate 10 mounted with the address electrodes 12, a desired thickness of lower dielectric thick film 14 for generating a wall charge and a barrier rib 16 for dividing discharge cells are sequentially formed. A desired thickness of fluorescent film 18 is coated on the surface of the lower dielectric thick film 14 and the wall surface of the barrier rib 16. At the bottom side of the upper glass substrate 20 mounted with the sustaining electrode pair 22, an upper dielectric thick film 24 and a protective film 26 are sequentially formed. The upper dielectric thick film 24 generates a wall charge like the lower dielectric thick film 14, and the protective film 26 protects the upper dielectric thick film 24 from an impact due to a gas ion during plasma discharge.
The conventional driving principle of the PDP will be described in conjunction with FIG. 2. As shown in FIG. 2, a panel 30 has n first sustaining electrodes Y1 to Yn and n second sustaining electrodes Z1 to Zn arranged alternately in parallel to each other m address electrodes Al to Am are arranged perpendicularly to the first and second sustaining electrodes Y1 to Yn and Z1 to Zn discharge cells 32 are provided at each intersection between the address electrodes Am and the first and second sustaining electrodes Yn and Zn. The discharge cells 32 are divided by the barrier ribs 16 and a mixture gas of He+Xe or Ne+Xe is sealed into the discharge cells 32. If a desired voltage is applied between the address electrode 12 and the first sustaining electrode Yn to drive the PDP, then an address discharge is generated to select the discharge cells 32. At this time, a wall charge is accumulated in the discharge cells 32 by the address discharge to lower a voltage for the sustaining discharge. Subsequently, if a desired voltage is applied between the first and second sustaining electrodes Yn and Zn only at the cells selected by the address discharge, then vacuum ultraviolet rays are generated by the sustaining discharge. At this time, fluorescent materials included in the fluorescent film 18 with red(R), green(G) and blue(B) colors is radiated by the vacuum ultraviolet rays to thereby emit R, G and B visible light rays. The visible rays generated from the fluorescent film 18 are emitted by way of the upper glass substrate 20 to thereby display a picture including characters and graphics.
Generally, a cathode ray tube(CRT) controls an intensity of an electron beam irradiated onto the fluorescent body so as to express the gray scale of a picture. However, since it is difficult the PDP of AC system to control a discharge intensity by such a method, the PDP of AC system expresses the gray scale of a picture by controlling a discharge frequency per hour. In other words, when it is assumed that a time displaying a single image on the entire screen once and sustaining the image be one frame, one frame is divided into n sub-fields. Each cell is turned on only at the corresponding sub-field in each sub-field to generate a discharge, whereas it is turned off at the other sub-fields not to generate a discharge. Accordingly, the brightness of each cell is determined by combining a discharge frequency at the discharged sub-field to thereby implement a gray scale of 2n. A typical gray scale implementation method based on the concept as described above includes the addressing and display separation(ADS) system. The ADS system will be described in conjunction with FIG. 3 below.
FIG. 3 is a view for explaining the conventional PDP driving method. As shown in FIG. 3, one frame is divided into 8 sub-fields SF1 to SF8 so as to implement 256 gray scales. Each sub-field is divided into a reset interval, an address interval and a sustaining interval and then driven.
The reset interval is a time period for initializing a screen by writing the entire screen simultaneously and thereafter erasing the entire screen. To this end, a writing pulse is applied between the first sustaining electrodes Y1 to Yn and the second sustaining electrodes Z1 to Zn simultaneously to turn on all the cells on the screen. Subsequently, an erasing pulse is applied between the first sustaining electrodes Y1 to Yn and the second sustaining electrodes Z1 to Zn simultaneously to turn off all the cells on the screen, thereby initializing the entire screen.
The address interval is a time period for selectively discharging only the cells to be turned on at the corresponding sub-field. To this end, xe2x88x92Vs voltage is applied to the first sustaining electrode at a line intended to perform an addressing, whereas Va voltage is applied only to the address electrode at the cell to be turned on in mxc3x973 cells connected to the first sustaining electrodes. At this time, since the sum of Va voltage and Vs voltage is higher than a critical voltage required for a discharge, an address discharge is generated at the cell applied with Va to form a wall charge. Also, since the Vs voltage is lower than the critical voltage, the cell applied with Va does not generate an address discharge. When such a process is sequentially and repeatedly performed n times with respect to n horizontal lines, nxc3x97(3m) cells are addressed.
In the sustaining interval, only the cell generating an address discharge performs a sustaining discharge to display and sustain the cell turned on. To this end, a sustaining pulse having Vs voltage is alternately applied between the first and second sustaining electrodes Yl to Yn and Z1 to Zn in a state in which OV is applied to the address electrodes Al to Am. When one frame is divided into 8 sub-fields, a weighting value of 1:2:4:8: . . . :128 ratio is given in the sustaining interval to express a gray scale by the combination of the sustaining intervals. The sub-field intervals corresponding to each bit are displayed in a sequence of SF1, SF2, SF3, SF4, SF5, SF6, SF7 and SF8.
Meanwhile, since each sub-field SF1 to SF8 has different sustaining intervals while having an interval for resting and addressing the entire screen, the reset and addressing intervals becomes same at the 8 sub-field. An efficiency of an ADS system in which a time for one frame is 16.67ms(i.e., {fraction (1/60)} second) will be calculated. Assuming that a time required for a resetting per one sub-field be 200xcexcs, since one frame is 200xcexcs xc3x978 sub-fields, a time of about 1.6ms is required. Also, assuming that a time required for an address interval be 3 xcexcs, since one frame having 480 horizontal lines is 200 xcexcsxc3x97480 lines xc3x978 sub-fields, a time of about 11.52 ms is required. In this case, a sustaining interval contributing to the real brightness in the entire frame time of 16.67 ms is 3.55 ms, a low light efficiency of 20.1% is obtained. As a result, the conventional PDP has a problem in that it is difficult to obtain a sufficient brightness level and hence the brightness is deteriorated.
Accordingly, it is an object of the present invention to provide a plasma display panel driving method and apparatus that is capable of improving the brightness of a plasma display panel.
In order to achieve these and other objects of the invention, a plasma display panel driving method according to one aspect of the present invention divides a screen into at least two blocks along scanning lines, and allows other blocks to perform the sustaining process during a time interval when a certain block performs the addressing process.
A plasma display panel driving apparatus according to another aspect of the present invention includes a plasma panel having a number of cells, said cells including a plurality of address electrode lines, scanning and sustaining electrode lines formed to be opposed perpendicularly every the address electrode lines, and common sustaining electrode lines formed to be parallel with the scanning and sustaining electrode lines; an address electrode driver for driving the address electrode lines; a scanning and sustaining electrode driver for dividing the scanning and sustaining electrode lines into at least two parts and driving each part sequentially; a common sustaining electrode driver for dividing the common sustaining electrode line into at least two parts and driving each part commonly; and a memory and controller for controlling a timing of each of the drivers and storing an input data.